PROCESSING CHARACTERlSTICS 0F
SELECTED POTATO CLONES

'a‘hesis for the Degree of M. S.
MICHIGAN STATE UNIVERSWY
LYNN RANDALL POPE
1969

  
   
   

  

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ABSTRACT
PROCESSING CHARACTERISTICS OF SELECTED POTATO CLONES.

By
Lynn Randall Pope

Nine selected potato clones, including two Solanum
tuberosum -Ԥ. stoloniferum species hybrids were processed
into potato chips, french fries and flakes. The varieties,
Kennebec and Russet Burbank were used as controls.

Data obtained from analysis of the raw material and
the products made from each clone was used to reach a conclusion
as to whether the clone would have potential as a commercial
variety. The hybrid clones were considered seperately because
of their unique properties. Clones 1111-2, 706-32 and 706-3h
were unacceptable because the products made from them were of
dark color. the product yields were low and the texture of the
french fries were poor in comparison to the control.
Clones 709, 711-8 and 58 were considered marginal. Their yield
and total solids content was acceptable but the color and
texture characteristics were mixed. One clone. 711-3 was
considered to have potential as a commercial variety. The
hybrid clones had a high solids content and were generally
better in other respects. They have a pronounced yellow flesh
due to xanthophyll pigments. In flakes antioxidants must be
used to prevent pigment destruction during storage. The fried

products have a flavor and texture different from the controls.

PROCESSING CHARACTERISTICS OF
SELECTED POTATO CLONES
By

Lynn Randall Pope

A THESIS

Submitted to
Michigan State University
in partial fulfillment of the requirements

for the degree of

MASTER OF SCIENCE
Department of Food Science
1969

ACKNOWLEDGEMENTS

The author is appreciative of the assistance and helpful
suggestions of his major professor, Dr. Clifford L. Bedford,
throughout the course of this work and during preparation of
this manuscript.

The author also wishes to acknowledge the assistance of
Professor Norman R. Thompson throughout this work and for
providing the raw material used, and Professor Charles M. Stine
for his suggestions and assistance in preparing this manuscript.

The author also extends his appreciation to those friends
and associates who made many helpful suggestions and gave up

substantial amounts of their time to help process the potatoes.

11

TABLE OF

Acknowledgements. . . . .
List of Tables . . . . .
List of Figures . . . . .
Introduction . . . . . .
Literature Review . . . .
Color. . . . . . .
Flavor . . . . . .
Texture . . . . . .
Yield. . . . . . .
Methods and Materials . . .
Raw Material . . . .
Storage . . . . .
Processing Procedures .
Analytical Procedures .
Results and Discussion. . .
Raw Material . . . .
Potato Chips . . . .
French Fries . . . .
Potato Flakes . . . .
Potato Flake Stability .
Summary and Conclusions . .
References. . . . . . .
Appendix A. . . . . . .
Appendix B. . . . . . .

CONTENTS

111

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LIST OF TABLES

TABLE

I. Additive per 10 lb of 20% Solids Mash .

II. Specific Gravity and Yield of Potatoes

III. Total Solids Content . . .
IV. Reducing Sugars . . . . .
V. Potato Chip Yield. . . . .
VI. Potato Chip Moisture . . .
VII. Potato Chip Oil Absorption .
VIII. Potato Chip Bulk Density .
IX. Potato Chip Hunter L Values .
X. Potato Chip Hunter a/b Ratio .
XI. French Fry Yield. . . . .
XII. French Fry Peeling Loss . .
XIII. French Fry Moisture Content
XIV. French Fry Oil Absorption .
XV. French Fry Maximum Show Force
XVI. U. S. D. A. French Fry Color
XVII. French Fry Hunter L Values.
XVIII. French Fry Hunter b Values
XIX. Potato Flake Peeling Loss .
XX. Potato Flake Thickness. . .

IV

Page

12
18
19
19
20

22
24
24
25
26
26
27
27
29
31
31
32
33
33

TABLE v Page
XXI. Potato Flake Yield. . . . . . . . . . . . 3n

XXII. Potato Mash Solids Content. . . . . . . . . 3h

XXIII.. Potato Flake Bulk Density.

XXIV. Potato Flake Production Rate,. . . . . . . . 36

XXV. Potato Flake Moisture Content . . . . . . . . 37

XXVI. Potato Flake Blue Value. . . . . . . . . . 37

XXVII. Potato Flake Hunter L. Values . . . . . . . 38

XXVIII. Potato Flake Hunter b Values . . . . . . o 39

XXIX. Stability of Hunter L and b Values in
Flakes Without Antioxidant. . . . . . . . . 40

XXX. Stability of Hunter L and b'Values in
Flakes With Antioxidant o o o o o o o o o o LEO

XXXI. Maximum.Absorbance of Pigment Extract from
Flakes Without Antioxidant. . . . . . . . . #3

XXXII. Maximum Absorbance of Pigment Extract
From Flakes With Antioxidant. . . . . . . . #3

LIST OF FIGURES

FIGURE
I. gnstgon Shear Force Curves of 706-32 and
22" o o o o o o o o o o o o o o 0

II. Visible Spectra of Pigment Extracts
from 322-6. (Without Antioxidant). . . . .

III. Instron Shear Force Curves of French
Fries O O 0 O O O O O C I O 0 O 0

IV. Instron Shear Force Curves of French
Fries O O I O O O O O O O O O 0 O

V. Visible Spectra of Pigment Extracts from
Russet Burbank (Without Antioxidant) . . . .

VI. Visible Spectra of Pigment Extracts from
Russet Burbank (With Antioxidant) . . . . .

VII. Visible Spectra of Pigment Extracts from
322-6. (With Mt10x1dmt) o o o o o o 0

VIII. Visible Spectra of Pigment Extracts from

IX. Visible Spectra of Pigment Extracts from 321-65
(With Antioxidant) . . . . . . . . . .

vi

Page

30

#2

5h

55

56

57

58

59

6O

INTRODUCTION

Potatoes were first cultivated by the natives of South
America more than 2000 years ago. The Spanish explorers first
discovered the potato in 1537. Exactly when or how the potato
was introduced into Europe is not clear. Its value as a food
was not recognized for sometime and it did not become important
until the 17th century. The use and importance of the potato
as a food, especially for the lower classes then grew rapidly.
The potato was returned to the Western Hemisphere in 1719 to
Londonderry. New Hampshire by Scottish-Irish immigrants.
By the 19th century in the United States, interest in potatoes
had grown extensively and plant breeders turned out hundreds
of new varieties, only a few of which were successful.
(Smith, 1968).

Potato production peaked in the period between World
War I and World War II. Per capita consumption declined after
the Great Depression until the advances in processing in the mid-
1950's stimulated expanded consumption of potatoes. In 1966,
12.2 million tons of potatoes were produced in the U. 3.. with
consumption at about 110 lb per capita. The growth of process-
ing is demonstrated by the fact that in 1956, 14% of all potatoes
for food use were processed, while by 1966 #15 were processed.
(Smith, 1968).

Early plant breeders were interested primarily in devel-

oping high yielding varieties with resistance to disease and

2
insects. With the development of processing it was recog-
nized that in addition to these goals. varieties need to
be developed for specific processing applications. For example,
the level of reducing sugars, which is determined by meta-
bolic activity, is related to potato chip color. It is believed
that through genetic selection, control of the enZymes gover-
ning the level of reducing sugars and thereby, color, could
be attained. (Treadway, 1961).

The purpose of this study was to determine the proc-
essing qualities of new selected clones. Potato chips, french
fries and potato flakes were made from nine new clones, in-
cluding two Solanum tuberosum - S. stoloniferum hybrids,

and evaluated to determine their processing suitability.
LITERATURE REVIEW

Until recently. when processing became an important
outlet for the potato crop. plant breeders had concentrated
on developing new varieties with high yields and resistance to
insects or diseases or other characteristics, such as frost
resistance and ability to withstand drought. The late blight
outbreaks of the mid-19th century in particular, stimulated
attempts to breed resistant varieties. (Talburt and Smith, 1967.)
It is now recognized that characteristics which are important
in processing can also be incorporated in a breeding program.
When studying the processing characteristics of several
varieties. Isleib (1962). found that variety pg; s3. is not
a valid criterion for predicting potato flake quality. It

appeared that growing and storage conditions have a definite

3
influence upon the quality of flakes made from the same
variety. This means that in evaluating new varieties for
their processing characteristics, one must use a standard
commercial variety grown and stored in the same manner as the
test varieties to remove bias due to the conditions encountered.

There are a number of general attributes of processed
potato products which must be considered in evaluating a new
variety for its processing suitability. These include color,
flavor, texture and product yield. Within these classifications,
limits are often established above or below which a product is
considered unacceptable.

QQLQR. Several factors are related to the color of
potato products. In addition to variety and growing conditions,
enzymatic and non-enzymatic browning, after cooking darkening
greening and natural pigmentation determine the color of
processed products.

The most familiar is nonenzymatic browning. This is
a reaction between an amino compound and a free carbonyl group
which proceeds from the formation of a Schiff's base through
Amadori rearrangement and Strecker degradation to compounds
which polymerize to form the characteristic brown pigments.
(Braverman. 1963). In potatoes the reactants are reducing
sugars and free amino acids. Habib and Brown, (1957) found
glucose and fructose to be the most generally present reducing
sugars. They concluded that low reducing sugars and low basic
amino acids are related to light colored chips. Hoover and
Xander (1961) found a consistent correlation only between glu-

cose and fructose levels and chip color. Other compounds,

u
including amino acids and minerals gave inconsistent correlations.

Similiar results have been reported by other workers,
(Shallenberger 1959: Fitzpatrick, 1965, 1966). The level
of reducing sugars and free amino acids depends upon variety and
storage conditions. Varieties having low solids tend to accum-
ulate more reducing sugars than varieties of high solids. Low
storage temperatures stimulate the accumulation of reducing
sugars. Generally this occurs at temperatures below 50°F and
increases as the temperature approaches freezing. The level
of browning reactants may be reduced by storing the potatoes
at high temperatures for several weeks. Maximum reducing sugar
ordinarily permissible for potato chip production is 0.2%,
fresh weight basis. Similiar limits for french fries and
flakes are reported to be 0.“ - 0.6% and 1.0% respectively
(Talburt and Smith, 1967).

Injured potato tissue is subject to enzymatic browning
which can result in an undesirable discoloration or the finished
product. Enzymatic browning results from the reaction of a
polyphenol oxidase with a phenolic compound to form red to
brown melanin pigments. In potatoes, tyrosine is believed
to be the major phenol involved. In normal processing, peeling
of the potatoes is the point at which this type of discoloration
occurs. The most commonly used preventative treatment is to
dip the freshly peeled potatoes in an acidified solution of
sodium sulfite or sodium bisulfite at a level of 1000 ppm 802.
(Talburt and Smith, 1967).

After cooking darkening is another undesirable factor

5

affecting the appearance of processed potatoes. It is generally
recognized as being due to the development of a colored complex
between ferric ions and an orthodihydric phenol. Chlorogenic
acid is usually implicated as the phenol. Many factors are
involved in aftercooking darkening, for example, pH, organic
acid composition, iron content, orthodiphenol content and the
availability of oxygen. This problem can be easily avoided by
treating the potatoes with a 2% solution of sodium acid pyro-
phosphate (fine particle size, fast acting food grade is rec-
ommended.) In practice this is done with french fries at the
blanching step or with potatoes for flakes at the precooking
step. (Smith, 1968).

Greening is a factor of importance to producers and
processors of potatoes. It is due to the formation of
chlorophyll under the peel, resulting from exposure to light.

It is undesirable from the standpoint of appearance and also

the bitter flavor which develops coincidentally and is attri—
buted to solanine. Greening is reported to be affected by
variety, maturity and age, temperature, intensity and quality

of light and duration of exposure. The most effective preventive
measure is to avoid exposure to light. (Smith, 1968).

Carotenoids are not normally important to the appearance
of commercially produced potatoes in the United States.
However, the Solanum tuberosum - S. stoloniferum hybrids used
in this study have a pronounced yellow color which affects the
appearance of the products made from them, particularly the

flakes. Brunstetter and Wiseman, (1947) reported that Katahdin

6
variety contains 3 ppm carotenoid, dry weight. They reported
the composition to be lutein, 0.50-0.77 ppm: beta-carotene, 0.30
ppm; aurochrome, 0.11 ppm, and several others unidentified.
Pendlington et.al. (1965), reported the carotenoid composition
of six British varieties to be similiar, containing beta-carotene,
beta-carotene-5,6-monoepoxide, cryptoxanthin -5,6-diepoxide,
lutein, cis-violaxanthin, cis-antheraxanthin-S,6-monoepoxide,
cis-neoxanthin and an unknown. The physical state of the
pigments has been found to affect the color of vegetables after
processing. Purcell et.a1. (1969) found that in some highly
colored vegetables with distinct chromoplasts containing the
carotenoid pigments, heating caused them to breakdown and
release the pigments into the cell where they Joined the lipids
to form colored droplets near the cell wall. Heating suf-
ficient to break down the cell resulted in the pigments
being dispersed throughout the cellular debris coloring it,
with a few droplets remaining intact. Purcell (1962) found
that the various carotene and xantophyll pigments of dehydrated
sweet potato flakes are neither preferentially spared or oxidized
in storage. Processing apparently did not destroy the caroten-
oids and the use of low temperature storage, nitrogen atmos-
phere and antioxidants decreased the loss of pigment.

Flavor. The flavor of potatoes is mild and problems
with the flavor ordinarily are those of off-flavors. The
natural flavor of potatoes arises from the reaction of
precursor compounds. Included are amino acids, sugars and

pectin. Factors which change these constituents can be expected

7
to change the flavor of the potato products. The major volatile
substances of cooked potato include various sulfur compounds,
aldehydes, alcohols, ketones and amines. In the deep fat fried
products, frying results in the development of different flavor
constituents. If these products are stored for some time under
unfavorable conditions rancidity will develop. Hexanal is
reported to be associated with the development of rancidity in
potato chips. Dehydrated potato products have a great tendency
to suffer from off-flavor problems.' This is due to the low
, moisture content and large surface area exposed to the air.
The principle fatty acids in the lipid fraction of Russet Bur-
bank potatoes is reported to be linoleic, linolenic, stearic
and palmitic acids. Oxidation of linoleic and linolenic acids
is closely related to the development of off-flavors in the
reconstituted product. Hexanal is a major product of autoxida-
tion. It is reported to increase with time in granules stored
in oxygen. The addition of ERA and BHT resulted in less hex-
anal production. (Smith, 1968).

Texture. The texture of potato products, especially
french fries and flakes is related to specific gravity,
total solids, starch content, and alcohol insoluble solids.
High values are associated with mealiness, dryness and slough-
ing. low values are associated with waxiness and lack of
sloughing. Storage temperature and time can affect texture
through changes in composition. Texture is important in
processing, particularly of flakes since the nature of the

process promotes cell breakage, if care is not taken, resulting

8

in an undesirable,pasty product. In addition to gentle
mashing and mixing to minimize cell breakage, precooking
followed by cooling is used to render the starch less soluble
and sodium acid pyrophosphate is also used to insolublize the
starch. Microscopic observation has shown that SAPP prevents
the starch from spilling out of broken cells. It is believed
that the phosphates may increase cross-bonding in the starch
rendering it less soluble. (Smith, 1968).

Ygglg. Product yield is of economic importance to
producers and processors. The most important factor governing
the yield of chips is the total solids content. Factors which
affect total solids will affect the yield. Some of these factors
include variety, cultural conditions, maturity and environmental
conditions. (Smith, 1968). The yield of french fries and flakes
also depends upon dry matter content. Peeling losses vary
between varieties and the amount of loss will affect the yield
obtained. Other factors which influence yield are variations
in moisture and oil content of the product and cull out due to
greening, scab, black spot and other physiological disorders.

METHODS AND MATERIALS

Raw‘Material. The potato samples used in this study
were obtained from the Montcalm County Experiment Station
Farm through the Department of Crop and Soil Sciences. The
samples were brought to the Food Science Department immediately
after harvest and placed in h5°F storage. The clones and
varieties were harvested during the month of October as they
became mature. Additional samples from the same source that

were stored at approximately “5°F, were obtained on 18 November,

9

and the first week of December 68 and on 8 January 69. At
the time of harvest, yields per acre and the specific gravity
of all lots were determined. Specific gravity was determined
using the method of Isleib and Thompson (1957).

The numerically designated clones used in this research
were 709, 58, 1111-2. 711-3, 711-8, 706-32, 706-3h, 321—65,
and 322-6. The two commercial varieties used as controls were
Russet Burbank and Kennebec. Russet Burbank was the control
for french fries and potato flakes and Kennebec was the control
for chips. The Solanum tuberosum - S. stoloniferum species
hybrids used are designated 321-65 and 322-6.

Storage. The potatoes were stored at 45°F and 70% to
80% relative humidity. The french fries and flakes were produced
from potatoes directly from storage. The initial potato chip
lots were also produced directly from storage, but since the
color was unsatisfactory all subsequent lots were conditioned
at 70°F and 80% to 85% relative humidity for 20 days before
chipping.

Processing Procedures. The procedures used for proces-
sing the potatoes are as follows:

Potato Chips:

1.) One to three pound random samples were taken
from storage for processing immediately or
conditioned for processing.

2.) Potatoes were washed, out in half and sliced
into 1/16 inch slices with a §ligg_ghig§
Senior vegetable slicer.

3.) The slices were washed in hot water for 1-2

minutes to remove free starch and thoroughly
drained and weighed.

u.)

5.)

6.)

10

Slices were fried in a General Electric
Model HK3 deep fat frier at 375°F. in hydro-
genated vegetable oil for 3 to 5 minutes.
The finish point was when the slices ceased
bubbling.

Slices were drained and cooled on absorbant
paper for 3-5 minutes, weighed and trans-
ferred to polyethylene bags.

Analysis was begun the day after processing
and sensory evaluation was scheduled within
a week of processing.

French Fries:

i.)

2.)

3.)

u.)

5.)

60)

7.)

8.)

9.)

Three to six pound random samples were taken
from storage for processing.

Potatoes were washed and preheated in water
at 1700?. for two minutes.

They were transferred to a 15% - 20% lye
solution at 165°F = 170°F and allowed to

soak with constant turning for 4 minutes.

The time was occasionally varied 1,.5 minutes
to account for differences in the peel.

Peel and lye were washed off with a hot water
spray, defects were trimmed away and the tubers
were held in a 1000 ppm 302 solution approx-
imately 1-3 minutes until sliced.

Tubers were sliced into 3/8 inch strips long-
itudinally, washed, nubbins and slivers re-
moved and weighed.

Samples for reducing sugar and solids deter-
mination were removed and the strips were
reweighed.

Strips were blanched for five minutes in water
at 190°F - 200°F.

The water was drained off thoroughly and the
strips were fried for 3% minutes at 375°F in
hydrogenated vegetable oil, drained on absor-
bant paper and cooled with the aid of a fan
for 5-6 minutes.

French fries were transferred to polyethylene
bags and stored at -10°F. Sensory evaluations
were made after about two months. Analysis

11

on all, samples were made after three to
eight months.

Potato Flakes:

i.)

2.)

3.)

u.)

5.)

6.)

7.)

8.)

9.)

10.)

A in to 8h pound sample was taken randomly
from storage for processing.

The condition of the tubers was noted, they
were washed, and preheated at 170°F for two
minutes in water.

Peeling and trimming was carried out as for
the french fries.

Potatoes were sliced into 3/8 inch slices,
drained, weighed and returned to the 302
solution.

Slices were wasned with running water for

1-2 minutes and precooked for 20 minutes in
165°F water, or for the second and third proc-
essing times, in 2% solution of SAPP.

The slices were cooled to 70°F - 80°F in a
cold water bath, taken out and allowed to
stand for 20 minutes before transferring
them to a retort for steaming at 212°F for
30 minutes.

Ricing was done using a Kitchen Aid Model
K-5A mixer with the coarse rotary grater
attachment. Additives or diluting water
were added at this point. Samples were
removed for solids analysis before additives
were incorporated.

The mash was dried on an Overton Machine Com-
pany Model P-36 double drum dryer, 12 inch
diameter by 19 1/8 inch length. One drum

was used as an applicator roll, the other as
a drying roll. Simulation of one to five
applicator rolls is possible by a doctor
blade control. Conditions normally used

were 8 rpm, u layers, uncooled applicator
roll and 85-90 psi steam pressure.

Production rate in 1b/ft2/hr was obtained
and drying characteristics were noted.

The sheets were placed in a polyethylene bag.
At the end of processing the sheets were re-
duced to flakes using a rotary slicer with
3/8 inch spacing between blades.

12
11.) Analysis was begun within one day of com-
pleting processing and sensory evaluation
was scheduled within a week. Samples for
storage stability were also prepared within
a week after processing.

A portion of the flakes produced initially and after
three months from Russet Burbank, 321-65 and 322-6 were also
placed in No. 2 cans, sealed in air and stored at -10°F and
75°F. Analyses were made after 0, 3 and 6 month storage. The
second lot of flakes produced had additives included to deter-
mine its effect upon stability of the color. The additive

mixture used is listed in Table I.

 

Table I.
Additive per 10 1b of 20% solids mash.

 

Ingredient Amount

Tenox IV (BRA and BHT)* . . . . . . . . 0.758
Myverol 18-07 (monoglyceride)*. . . . . 1.00g
Skimmilk Solids . . . . . . . . . . . . 2.00g
Sodium Sulfite . . . . . . . . . . . . 0.60g
Sodium Bisulfite. . . . . . . . . . . . 0.20g

 

* obtained from Eastman Chemical Company

The level of ERA and BHT (Tenox IV) used in the flakes was 66
ppm wet basis or 310 ppm 6% moisture basis.

Analytical Procedures. The procedures used for anal-
yzing the raw and processed potatoes were as follows.

Reducing Sugars. Raw potato strips obtained during
french fry processing were macerated in a Waring blender for
1-2 minutes. The juice (5-10 ml) was transferred to a test
tube and the reducing sugar determined using the Dextrocheck
method (Ames Company, Division of Miles Laboratories). If there

was a delay in analysis the samples were refrigerated at 38°F.

13

French Fry Preparation. The frozen french fries were
prepared for analysis by taking them from -10°F storage and
allowing them to thaw for #5 to 60 minutes. The samples were
then fried for 0.5 minute in 375°F hydrogenated vegetable oil.
The samples were taken hot for analysis. USDA color was
determined immediately and texture was tested 2-3 minutes after
frying, followed by color and moisture.

Moisture Content. The vacuum oven method was used.
(A.O.A.C. Methods 2: Analysis p. 308). The samples were dried
at 70°C and 26-28 inches Hg for 12-14 hours. The moisture of
the raw potato was determined by taking samples of raw french
fry strips, macerating them in a Waring blender for 1-3 minutes
and placing 9-12g of the well mixed sample in previously dried,
tared glass petri dish. The samples were dried to constant
weight. The moisture content of the potato mash was determined
in the same way except blending was unnecessary. Potato chips
were broken using a spatula to minimize loss of oil from the
surface. Samples of 9-12 g were placed in dried, tared Soxhlet
thimbles and dried. French fry samples were macerated for 1-3
minutes in a Waring blender, 9-12 g of well mixed sample was
placed in a dried tared Soxhlet thimble and dried.

The moisture content of the potato flakes was deter-
mined using a Cenco Infrared Moisture Balance method. All
moisture determinations were Made in triplicate.

Oil Content. The oil content of potato chips and french
fries was determined by the Soxhlet method (Jacobs, 1958). The
dried potato chips and french fries were continuously extracted

for 12 hours with petroleum ether (B.P. 30°- 60°C.) at a rate

14
of 3-5 drops per second.

Color. French fry color was determined using the USDA
color standards. The finish fried strips were compared to the
standards and the color value recorded. The Hunter Color and
Color Difference Meter, Model D25L, was used to determine the
color of the french fries, chips and flakes. The french fries
were laid in a four inch glass sample dish in a manner, and
to a depth that minimized light transmission. The samples
were presented to the instrument and read through the bottom
of the dish. Two readings were taken on each sample at 90° with
respect to each other and the values averaged. An enclosure of
flat-black poster board was built over the viewing port to
eliminate interference from outside light. Potato chip color
was determined similarly. The chips were placed in the dish
and compressed with a beaker. Sufficient chips were added to
minimize light transmission. Potato flakes were placed in the
dish to fill it and the dish was gently tapped to settle the
flakes. Color standard #2810, L=94.8, a=-0.7, b=2.7, was used
for flakes and standard #2814, L=83.0, a=-3.5, b=26.5 was used
for french fries and chips.

Bulk Density. The method of Bakker-Arkema, et.al. (1968)
was modified to determine the bulk density of potato chips and
flakes. A 100g sample of chips was placed in a 2000 ml graduate
cylinder. The cylinder was lifted to a height of 2% inches and
dropped 50 times, turning it slightly after each drop. The
flake method was similar except a 50g sample was used in a
1000 ml graduate cylinder and it was dropped from a height
of 3 inches. Bulk Density was calculated in lb/ft3 from the

15
packed volume. The determination was made in duplicate for
chips and in triplicate for flakes.

French Fry Texture. Texture was characterized by a
modified form of the method of Ross and Porter (1966, 1968,
1969). An Instron Universal Testing Instrument, Model TT-BM was
used. The shear cell had a single blade with dimensions 1/8
inches wide by 2 9/16 inches long. The operating conditions
were the 1 kg to 50 kg load cell used in the 10 kg full scale
position, 5 cm/min chart and crosshead speed. French fry strips
were placed in the shear cell in one layer seven strips wide.
The maximum shear force is reported as the average of three
tests. Representative curves are also reported.

Blue Value. Cording's (1959) modification of the
method by Mullins (1955) was used. The determination was made
in triplicate.

Flake Thickness. A micrometer was used to measure the
thickness of the flakes. Six to eight random measurements were
taken to arrive at a representative value.

Production Rate. The weight of product from a timed
run on the drum dryer was used to calculate drum drying rate in
1b/ft2/hr.

Yield. Potato chip yield is reported as:

(Wt. of chips) (100)

Wt. of slices

French fry yield as:

(Wt. of french fries; (100)
(Wt. of raw potatoes

 

16
Potato flake yield as: (6% moisture basis)
(100). (% Peeling ioss) (% Solids)

Sensory Evaluation. Potato chips were evaluated by
sensory panels after each processing time. The panel members
compared 709, 322-6 and 321-65 to Kennebec and recorded their
judgement of the degree of difference in color, flavor and
texture. Later panels judged whether the clones were better
or worse than the controls. The panels consisted of 18-20
people and were carried out in duplicate. Sensory evaluation
of the french fries was done in the same way as for the chips
except that care was taken to present the samples hot. Potato
flake evaluation was performed similarly. The flakes were made
into mashed potatoes by boiling four liters of water with ca
3.4g of table salt. To each 20g of flakes, 80 ml of boiling
water was added. The mashed potatoes were stirred until an
even consistency was attained. Each panel member was served ca
one-half ounce of each sample. The stored flakes were evaluated
after three months storage by the method above except that
only color and flavor were evaluated and the panel was asked
to compare the 75°F sample against the -10°F sample of each
clone or variety.

Pigment Extraction. Extractable color was determined
by a modification of the method of Wall and Kelly (1943).

A 5.00g sample of flakes was weighed out and placed in a
blender jar with 140 ml of hexane: 95% ethanol (3:2). The
sample was blended in a frothing mixture for five minutes and

then quantitatively transferred to a frittered glass funnel

17
with a suction flask and washed alternately, twice each, with
hexane and 95% ethanol. The extract was transferred quantitat-
ively to a 500 m1 separatory funnel and 100 ml of distilled
water was added followed by 50 ml of 5% sodium sulfate solution.
The mixture was swirled and allowed to separate. The lower
aqueous phase was transferred to a second separatory funnel
and extracted three times with 30 ml of hexane. These frac-
tions were transferred to the original hexane fraction. The
combined extract was carefully washed with 100 ml of distilled
water and transferred to an erlenmeyer flask through 100 mm
funnel containing a bed of anhydrous sodium sulfate to remove
the remaining water. The dried hexane extract was reduced in
a rotary vacuum evaporater and transferred quantitatively to a
10 ml volumetric flask. Extraction of the raw samples were
carried out in a similar manner, with the weight adjusted such
that the dry matter was equal to that in the corresponding
flakes. Maximum absorbance and a scan of the visible absorp-
tion spectra were determined on the samples using a Beckman DB
spectrophotometer standardized with hexane at 540 nm.

Thin Layer Chromatography. After the spectra were de-
termined, the 10 ml extract was evaporated under nitrogen to
3-4 ml. Approximately 30-50 ul was applied to an Eastman pre-
coated silica gel thin layer sheet. The sheets were previously
activated at 110°C for six minutes. The solvent system used was
Skellysolve B: Acetone: Methanol (89:10:1) and the sheets were
developed to 10 cm from the origin. The visualizing agent was

2‘, 7' -dichlorof1uorescein, 0.2% in 95% ethanol.

18
RESULTS AND DISCUSSION

Raw Material. The specific gravities of the clones
ranged from 1.070 to 1.109 (Table II) and there was a 92% cor-
relation between specific gravity and solids. The yields per
acre ranged from 201.0 to 421.6 hundred weight. Based on the

yield per acre ranged from 44.5 to 87.0 hundred weight.

 

Table II.
Specific Gravity and Yield of Potatoes

 

 

 

__lield

Sample Specific Gravity CWTl/acre cw'r1 solids/acre
Russet Burbank 1.089 NA2 NA2
Kennebec 1.075 421.6 82.2
322-6 1.095 201.0 44.5
711-3 1.080 388.1 84.5

58 1.079 317.0 66.5
709 1.075 415.1 79.5
711-8 1.075 397-5 87.0
706-32 1.074 381.5 71.0

 

l = Hundred weight, 2 = Not Available.

Total Solids.
1111-2 to 28.3% for 321-65 (Table 111.). the differences were

significant at the 1% level.

The solids content varied from 16.7% for

No significant changes occurred

in the solids content with time from November to March.

19

 

 

 

Table III
_ Total Solids Content
Sample Nov. Dec. Mar. :ZX; *
% Solids
321-65 28.3 26.0 26.5 26.9 I
322-6 22.1 24.1 22.9 23.0 ‘
Russet Burbank 24.1 23.2 21.3 22.9
711-3 21.8 22.1 21.7 21.9 1
711-8 21.9 21.2 18.7 20.6
Kennebec 19.5 18.8 22.1 20.1
706-34 18.6 19.2 20.6 19.5
709 19.0 19.5 19.9 19.5
58 21.0 18.5 18.3 19.5
706-32 18.6 17.3 16.6 19.3
1111-2 16.7 16.8 17.4 17.0

 

 

* Differences at 5% level, Duncan's Multiple Range Test.

Reducing Sugars. Significance at the 5% level was found
between clones and varieties. Reducing sugars varied from
0.05% to 1.0% in 321-65 and 1111-2 respectively (Table IV).

No difference with time in storage was observed.

 

ETEhle IV
Reducing Sugars
Sample Nov. 59cc.

3

m

H
*

% Reducing Sugar

321-65 0.05 0.2 0.05 0.1
322-6 0.4 0.05 0.1 0.2
Russet Burbank 0.1 0.4 0.2 0.2
Kennebec 0.2 0.4 0.2 0.3
711-3 0.2 0.4 0.4 0.3
58 0.2 0.6 0.4 0.4
709 0.6 0.2 0.8 0.5
706-32 0.4 0.6 0.6 0.5
706-314 0.6 O.“ 0.6 005
711-8 0.4 0.6 0.6 0.5
1111-2 00“ 1.0 0.6 007

 

 

 

* Differences at 5% level, Duncan's Multiple Range Test.

 

20

Physiological Condition. On 3 January, 321-65
and 706-32 were just beginning to sprout, and the tubers of
all of the lots were in good condition. Two months later
all of the potatoes were sprouting and the tubers of many were
flacid. Difficulty in maintaining the humidity high enough
was responsible in part for desiccation which occured.

Potato ghlp_. Yield varied from 23.1 to 32.8 lb/lOO
1b (Table V). Significant differences were found between clones
(1% level). The hybrids had a higher yield than the other
clones. A significant correlation coefficient of r= 0.73

(1% level) between yield and total solids content was also

 

 

 

 

 

 

found.
‘Table v

Potato Chgngield
Sample Nov. Dec . Map. Y *

Yield (lb/100 1b)
321-65 32.8 32.2 30.5 31.8 I
322-6 3003 3109 2907 30.6
Kennebec 27.9 30.1 28.0 28.7
711-3 26.6 28.4 26.4 27.1
706-34 25.0 27.5 27.8 26.8
58 25.8 26.6 27.8 26.7
709 27.9 27.1 24.0 26.3

 

* Differences 5% level, Duncan's Multiple Range Test.

Moisture.

There were no differences in moisture content

between clones or times of processing when careful control of

the chipping conditions were maintained.

Higher moisture levels

21
will occur when the frier is overloaded as occurred at the
March processing time (Table VI). Moisture varied from 1.3% to

2.5% in November and December and from 1.8 to 4.2% in March.

 

 

 

 

Table VI.
.- Potgpp Chip Moisture
Sample Nov. Dec. Mar.
Z Moisture*

Kennebec 2.0 2.0 3.9
322-6 205 2.3 1.8
709 2.1 1.8 3.2
1111-2 1.9 1.8 3.5
706-32 2.2 1.7 3.5
706.3“ 103 106 30""
711-3 202 203 L702
711-8 201 2.0 302
58 1.6 1.8 3.3

 

* Difference between times (5% level).
Oil Content. Oil absorption varied from 50.8% to-28.2%
(Table VII). Differences were significant between clones, but
not between processing times. Oil absorption was found to be

inversely related to total solids (r c -0.78, 1% level).

22

 

 

 

 

 

 

 

 

Table VII
Potato Chip Oil Absorption
Sample Nov. Dec. Mar. * .X
011

706-32 42.0 43.2 30.8 45.3
709 42.0 45.0 3.4 43.5
1111-2 41.4 44.4 44.2 43.3
706-34 39.6 40.3 42.7 40.9
Kennebec 40.8 37.6 42.4 40.3
58 40.4 38.6 39.3 39.4
711-8 35-7 39.0 38.3 37.?
711-3 33.7 37.6 38.9 36.7
322-6 33.5 35.8 33.1 I 34.1
321-65 32.3 34.9 28.2 31.8

 

* Differences at 5% level, Duncan's Multiple Range Test.
Bulk Density. Significant differences in bulk density
between clones was observed (Table VIII). The bulk density
varied from 3.8 lb/ft3 to 7.3 lb/ft3. Considerable variation
occured in the bulk density values which could be related to
variations in the size of the potato chips. Missing values
(Kennebec, March bulk density and 322-6, December peeling loss)
were calculated according to the method of Guenther (1964, p.77).
Color. Potato chips with high L values and low a/b
ratio are considered most desirable. The chips processed in
November without conditioning were found to be visually unac-
ceptable. This is shown in the significantly lower L values
and higher a/b ratios, compared to those processed in December
and March which were conditioned. There were also significant
differences between clones. Clones 709, 58, 706-32, 706-34 and
1111-2 did not respond well to conditioning and did not
produce satisfactorily light chips. High solids clones had
better color than the low solids clones (Tables IX and X).

24

 

 

Table VIII
Potato Chip Bulk Density

 

 

 

 

 

 

 

Sample Nov. Dec. Mar. * 7
Bulk Density, lb/rt3

321-65

321-65 702 503 703 606
322-6 5.9 “'08 702 6.0
Kennebec 5.9 2.3 (5.7)+ 5-6
709 6.1 .3 5.7 5.4
711-3 602 502 no” 503
706-34 5.5 4.4 4.3 4.7
58 4.9 4.5 4.3 4.6
711-8 308 502 “'06 “'05
706-32 4.3 4.5 3.9 4.2
1111-2 3.8 4.0 3.9 3-9

 

 

dummy value
* Differences at 5% level, Duncan's Multiple Range Test.

 

 

Table IX
Potato Chip Hunter L Values
Sample Nov. Dec . Mar . * X

 

Hunter'L Value ”‘

 

 

321-65 53.2 62.3 60.4 58.6
322-6 40.4 62.8 55.5 52.9
Kennebec 42.0 56.3 55.5 51.3
711-3 46.2 55.6 50.6 50.8
711-8 37.4 56.5 45.2 46.4
709 43.8 41.4 45.6 43.6
58 39.0 41.6 47.8 42.8
706-32 37.7 37.2 46.6 40.5
1111-2 36.2 36.4 36.0 36.2

 

 

* Differences at 5% level, Duncan's Multiple Range Test.

25

 

 

 

 

 

 

 

Table X
Potato Chip Hunter a/b Ratio
Sample Nov. Dec. Mar. X
Hunter aZb ratio
1111-2 0.56 0.51 0.46 0.51
706-34 0.63 0.46 0.38 0.49
58 0.54 0.48 0.31 0.44
706-32 0.51 0.52 0.29 0.44
709 0.42 0.43 0.33 0.39
711-8 0057 0019 0032 0036
711-3 0.42 0.19 0.25 0.29
Kennebec 0.46 0.18 0.17 0.27
322-6 0.51 0.02 0.13 0.22

 

* Differences at 5% level, Duncan's Multiple Range Test.

Sensory Evaluation. Potato chips made in November
were found to be different from Kennebec in color and flavor.
In addition, 321-65 and 322-6 were different from 709 in
color and 321-65 was different from 709 in flavor. Texture was
found to be different between Kennebec and 322-6 and 321-65.
The differences between_709 and the other clones is due to
greater nonenzymatic browning. The panel at the second proc-
essing time found all of the clones to be different from Kenn-
ebec in color, flavor and texture. For color and flavor, the
third panel found Kennebec, 321-65 and 322-6 different from
709 which was judged less acceptable. No texture differences
were observed.

French nggg. Yield, peeling loss and moisture con-

tent were not different for either times or clones. Yield varied

26
from 33.1 lb to 52.4 1b/100 1b (Table XI). Peeling loss was
found to range from 15.3% to 34.2% (Table XII). Table XIII
shows the moisture content of the french fries which varied

from 42.6% to 56.9%.

 

 

 

 

 

 

 

 

 

 

Table XI.
_:5 French Fry Yield
Sample Nov. Dec. Mar.
Yield (lb/100 1b)
321-65 52.4 48.8 47.9
Russet Burbank 48.4 45.8 41.7
711-8 45.6 45.0 46.1
711-3 .4 42.3 49. 5
322-6 45.2 41.7 44.1
58 44.5 40.0 47.1
706-34 33.2 47.8 47.1
709 36.9 43 5 47. 7
706-32 33.1 44. 3 46. 6
1111-2 33.4 39.2 468
Table XII.
_ French Fry Peeling Loss
Sample Nov. pec. Mar.
% Peeling Loss
Russet Burbank 21.5 24.3 23.8
321-65 18.2 24.0 22.1
322-6 18.1 23.0 22.8
709 20.2 20.8 20. 4
711-3 20.3 23.2 18. 3
58 21.1 25.3 19. 2
706-32 34.2 20.6 20. 7
1111-2 20.0 25.5 18.0

 

27

 

 

 

 

 

 

 

 

 

Table XIII
French Fry Moisture Content
Sample Nov. Dec. Mar.
% Moisture
Russet Burbank 50.3 49.9 47.0
321-65 43.9 42.6 44.9
322-6 48.9 45.0 44.4
711-3 49.6 47.8 50.9
711-8 54.4 51.8 52.9
709 56.7 51.4 56.9
706-34 53.2 53.7 56.4
1111-2 56.3 53-3 550
Table XIV
French Fry Oil Absorption
Sample 5Nov. Dec. Mar. X 3
5 Oil (Dry Basig)
706-32 29.5 31.3 30.8 30.5
1111-2 29.0 31.7 29.6 30.1
706-34 29.4 28.9 31.2 29.8 I
709 27.6 26.9 28.3 27.6
711-8 26.8 27.5 26.5 26.9
711-3 21.1 23.1 25.0 23.1
Russet Burbank 21.4 23.5 22.7 22.5
322-6 2107 1901 21.8 2009
321-65 21.2 19.1 20.8 20.4

 

*

Difference at 5% level, Duncan's Multiple Range Test.

28

011 Content. Differences in oil content at the 1% level.
were found between clones. Oil absorption ranged from 31.7%
to 19.1% (Table XIV). The correlation between solids and oil
content was r = -0.85, 1% significance. Storage time did not
affect the absorption of oil.

Texture. Instron Universal Testing Instrument maximum
shear force values differed between samples at the 1% level.
They varied from 3.0 kg to 7.3 kg and were significantly higher
for the higher solids clones. In addition to maximum force,
the shape of the curve is also related to the textural charac-
teristics. Figure I illustrates the differences in the curves
of two clones of different texture. Clone 322-6 (November) is
representative of a desirable, mealy textured french fry. It
has a pronounced crust burst peak followed by relaxation and a
long crust shear peak. Clone 706-32 (November), results in a
soggy french fry which is evident from the lack of a crust
burst and a lower crust shear peak. Representative curves from

the rest of the clones are found in the appendix A.

29

 

Table XV.
French Fry Maximum Shear Force

 

Sample Nov. Dec. Mar. X’ *
Maximum Force_(§g)

322-6

321-65

Russet Burbank
58

706-32

711-3

711-8

1111-2

706-34

709

wuwci-‘C'I-‘mmlr
. O O O O O O I 0
omc'tomoomxooo
wwcmmwwtmm
\omomoooooommxo
umwutwwmmfl
O O O O O O O I O O
O\} :umeooxmu
wwuwwttmmm
utmooxoomi—I Po

 

 

* Differences at 5% level, Duncan's Multiple Range Test.
Color. A significance at the 1% level between times and

clones was found for both the USDA color standards and Hunter
color values. USDA color varied from 0 to 4 and was darker for
1111-2, 706-32 and 706-34 (Table XVI). Increased storage time
gave lighter colored french fries. Hunter L values gave the
same general results (Table XVII). This was a good verification
of the subjective method as a quality control tool. Hunter
b values, a measure of yellowness, are significantly greater
for the hybrid clones due to their naturally greater pigmenta-
tion (Table XVIII).

Force (Kg)

30

Figure I.
Instron Shear Force Curves

of 706-32 and 322-6

322-6 (Nov)

706-32 (Nov)

 

Crust Burst
,_______

Crust
Shear

 

 

 

 

 

31

 

Table XVI
USDA French Fry Color

 

Sample Nov. .990. Mar. 2 *
USDA Color Values

1111-2 3 4 2 3.0
706-32 3 4 2 3.0
706-34 3 4 2 3.0
709 2 2 1 1.7
58 1 3 0 1.3
322-6 2 1 1 1.3
321-65 1 l 1 1.3
Russet Burbank 1 l 0 0.7

 

 

* Differences at 5% level, Duncan's Multiple Range Test.

 

 

 

Table XVII
French Fry Hunter L Values
Sgpples Nov. _*§ec. Ma35 X' *
Hunter L Values
321-65 52.2 54.6 54.4 53.7
Russet Burbank 40.2 49.6 55.8 51.9
322-6 47.2 54.4 53.6 51.7
711-3 47.7 46.2 52.2 48.2
58 42.4 40.8 51.1 44.8
709 41.0 44.0 48.6 44.5
711-8 44.9 39.6 47.8 44.1
706-32 40.2 31.2 44.4 38.6
706-34 40.4 31.2 43.5 38.4
1111-2 37.2 31.6 43.4 37.4

 

* Difference at 5% level, Duncan's Multiple Range Test.

32

 

Table XVIII
French Fry Hunter b Values

 

Sample Nov. Dec. Mar. 2 *

Hunter b Values

321-65 24.8 25.0 24.3 24.7
322-6 22.1 25.1 24.5 23.9
Russet Burbank 20.7 19.6 21.8 20.7
711-3 21.0 20.7 19.4 20.4
709 17.8 18.4 19.7 18.6
711-8 19.2 17.4 18.3 18.3
58 18.1 17.8 18.5 18.1
706-32 17.2 12.8 18.0 16.0
706-34 17.5 12.6 17.4 15.8

 

 

 

* Differences at 5% level, Duncan's Multiple Range Test.

Sensory Evaluation. The first lot of french fries were
found to be different from Russet Burbank in color, flavor
and texture. Differences were not significant in the last
two panels for any of the attributes. This is believed to
be due to the panels being divided as to whether the clones
were better or worse than the reference.

Potato Flakes. Peeling loss and flake thickness was
not different between clones or times. Peeling loss ranged
from 12.6% to 26.4% (Table XIX) and flake thickness varied from
0.004 inch to 0.008 inch (Table XX).

Yield. Differences between clones at the 5% level
were found. The high solids potatoes tended to have the higher
yield. Yield varied from 13.0 1b to 23.2 lb/100 1b. (Table
XXI). The correlation between solids and yield was r= 0.97.

1% level.

33

 

 

 

 

 

 

 

 

Table XIX
Potato Flake Peeling Loss
Sample .299. Mar. Apr.
5 Peeling Loss
Russet Burbank 21.3 22.7 19.7
709 12.6 24.7 18.0
1111-2 23.8 18.6 -
706-32 26.4 21.7 -
711-3 21.1 20.9 -
58 2&06 1906 -
322-6 (19.4) 19.9 23.7
Table XX
Potato Flake Thickness
Sample 'Dec. Mar. Apr.
Flake Thickness 1 1000 in.
Russet Burbank 7 6 7
709 5 4 5
1111-2 5 5 -
706-32 5 5 -
706-34 6 5 -
711-3 6 7 -
711-8 5 6 -
58 5 7 -
322-6 6 6 6
321-65 5 8 7

 

34

 

 

 

 

 

 

Table XXI
Potato Flake Yield
Sample Qec . Ma; . X * Apr .
Flake Yield (lbllOO 1b)

21-65 21.6 21. 21.6 23.2

22-6 19.1 21. 20.2 21.0
Russet Burbank 19.4 18.8 19.1 19.6
711-3 17.4 . 19.6 18.5 -
711-8 1506 1708 1602‘ "
58 14.8 1707 1602 "
709 18.1 14.1 16.1 17.5
1111-2 13.5 16.0 14.8 -
706-32 13.0 15.2 14.1 -

 

 

* Difference at 5% level, Duncan's Multiple Range Test.

 

 

 

 

 

 

Table XXII.
Potato Mash Solids Content
Simples ”Dec . Mar. 2 * Apr.
% Mash Solids
321-65 26.2 26.8 26.5 29.3
322-6 23.2 24.7 24.0 26.2
Russet Burbank 23.0 22.6 22.8 23.3
711-3 21.2 23.8 22.5 -
711-8 19.9 20.8 20.4 -
58 18.8 21.1 20.0 -
706-34 18.5 20.5 19.5 -
709 19.9 18.0 19.0 20.5
1111-2 1700 1809 1800 '-
706-32 1700 1807 1708 "’

 

 

* Differences at 5% level, Duncan's Multiple Range Test.

35

All of the yields are converted to a 6% moisture basis
for comparison purposes.

Mash Solids Content. Solids content was different
-between times and clones. Increases in solids with time
occured. Clone 321-65 was significantly higher than all of the
others, while 322-6, Russet Burbank and 711-3 followed in
solids content (Table XXII).

Bulk Density, Production Rate, Flake Moisture and Blue
Value. Differences were observed in all of these attributes
with processing times. This is attributed to the use of add-
itives at the second processing stage. All of the charac-
teristics were generally improved. In March all of the clones
were treated with sodium acid pyrophosphate and only Russet
Burbank, 709, 321-65 and 322-6 were treated with all of the add-
itives. Since no differences between clones occured, the
changes were logically attributed to the use of SAPP. Bulk
density was found to increase with time, and varied from 6.5
lb/ft3 to 9.2 1b/ft3 (Table XXIII). Table XXIV shows the
production rates obtained. They varied from 1.2 to 4.5 lb/ftZ/hr.

36

 

 

 

 

 

 

 

 

 

Table XXIII
Potato Flake Bulk Density
Samples Dec. Mar. Apr.
Bulk Density, lbéft3
Russet Burbank 9.2 8.4 8.8
709 6.7 8.7 8.8
1111-2 607 706 -
706-32 605 709 -
706.31+ 701 801 "
711-3 605 7.0 -
711-8 607 701 "
58 6.6 7.6 -
322-6 706 703 707
321-65 7.8 8.3 80h
Table XXIV
Potato Flake Production Rate
Samples :90: Mar. Apr.
Production Rate 1b/ftg/hr.
Russet Burbank 2.8 3.5 2.5
709 1.8 1.6 2.2
1111-2 1.4 2.0 -
706‘31‘.’ 107 2.1 "
711-3 109 [+05 "'
711-8 1014' 2.2 "’
58 1.7 4.5 -
322-6 206 203 201+
321-65 2011' [+00 207

 

3?
Flake moisture varied from 2.8% to 8.1% and tended to be higher

in the March samples (Table XXV). SAPP resulted in a very
large reduction in Blue Value in all cases (Table XXVI).
Blue value varied from 110 to 270 in the untreated samples

and from 44 to 112 in the treated samples.

 

 

 

 

 

 

 

 

Table XXV
Potato Flake Moisture Content
:Sample Dec. Mar. Apr.
% Moisture
Russet Burbank 6.6 7.7 8.5
709 3.2 4.4 4.4
1111-2 5.0 5.9 -
706-32 301‘" 30,4 "’
706-31; 208 3.4 -
711-3 306 “'05 -
58 2.8 8.1 "
322-6 3.7 5.3 5.6
321-65 306 506 6.8
Table XXVI
Potato Flake Blue Value
Sample 5ppec. Mgg. App.
ELM-.22
Russet Burbank 152 85 44
709 162 85 54
1111-2 152 80 -
706-32 270 112 -
706-34 245 97 -
711-3 110 97 -
711-8 178 95 -
58 158 85 -
322-6 170 80 60
321-65 205 104 44

 

38

Color. Hunter L and b values were different for
clones and L value was also different for times. The range
in L value was from 75.7 to 84.7, while b value varied from
14.0 to 24.8. Color was generally better for the second
processing time and with Russet Burbank, 321-65, 709 and 322-6.
It was noted that color improved with time for both french
fries and flakes. This must be due to some compositional
change in the potatoes other than reducing sugar content which
could not be related to color with time. The differences in
b value are due to the yellow pigments in the hybrid clones and
nonenzymatic browning which was evident in some of the clones

(Table XXVIII).

 

Table XXVII
Potato Flake Hunter L Values

 

 

Sample SDec. Mar. 3? *' Apr.

1

Hunter L Values

 

 

Russet Burbank 82.7 84.7 83.7 83.4
321-65 80.9 83.0 82.0 81.8
709 81.7 80.7 81.2 83.2
322-6 79.7 82.0 80.8 80.1
711-3 79.7 80.7 80.2 -
711-8 7802 82.0 80.1 "
58 78.8 81.0 79.7 -
1111-2 78.0 78.6 78.3 -
706-34 76.3 79.4 77.8 -
706-32 75.7 75.9 75.8 -

 

* Differences at 5% level, Duncan's Multiple Range Test.

39

 

Table XXVIII
Potato Flake Hunter b Values

 

 

 

 

 

Sample :Qec. Mar. X’ * Apr.
fighter b Value
322-6 24.8 24.3 24.6 24.0
321-65 22.6 24.5 23.6 24.0
706-34 22.6 20.6 21.6 -
706-32 2103 20.8 2100 '-
1111-2 21.14. 20.5 21.0 "
711-8 20.“, 18.8 19.6 -
711-3 20.2 18.1 19.2 -
58 1908 1706 1807 -
709 18.0 19.3 18.6 17.3
Russet Burbank 14.0 15.8 14.9' I 16.2

 

* Differences at 5% level, Duncan's Multiple Range Test.
Sensory Evaluation. The clones were judged to be diff-
erent in color from Russet Burbank. The difference in 709 was
not due to natural pigmentation, and was not evident from the
Hunter color values. Differences in flavor between 709, and
322-6 and Russet Burbank were also detected. Texture was dif-
ferent only for 709. Further sensory evaluation to determine
preferences was not conducted because of problems with the
flavor of the flakes containing additives.
Potato F1352 Stability. Flakes with no additive showed
no significant differences in Hunter L or b values between
the 0 and three and six month -10°F and 75°F lots. However,
the changes were visually apparent for the hybrid clones at

75°F. It is believed that the small amount of data was

40
probably the reason no statistical significance was obtained.

The flakes with antioxidantLdid not show any differences
(Tables XXIX and XXX).

 

Table XXIX.
Stability of Hunter L and b Values in
Flakes Without Antioxidant

 

Hunter L and b Values

 

 

 

 

   
  

 

 

 

 

 

 

 

 

Sample
Russet
Burbank 12.8 14.2 82.4 13.1
322-6 8008 19.0 80.2 1,403
321-65 81.2 21.4 81.2 13.0
Table XXX.
Stability of Hunter L and b Values in
Flakes.WithflAntiOxidant
Hunter L and b Values
0 mo. 3 mo.
-10 F 75°F

Sample L b L b L b
Russet Burbank 84.7 13.8 83.6 15.8 83.3 15.
322-6 82.0 2 .3 81.2 23.8 80.9 22.
321-65 83.0 24 5 82.5 24.6 81.0 22.6

 

 

41

Pigment Extract. The absorbance values reported in
Tables XXXI and XXXII are the absorbance maximas of the visible
absorption spectrum of the pigment extract. The maximas occured
at 440 nmt 5 nm. The maximas varied between the flake samples
depending upon clone or variety and the storage condition of
the flakes. The peaks were quite distinct for the extract from
raw potatoes and freshly made flakes. With storage the peaks
broadened, and became less clearly defined. Absorbance decreased
with storage time and was generally greater at -10°F than at
75°F. The loss of pigment was significant for the flakes
stored without antioxidant at 75°F, low temperature and antiox-
idant was found to be effective in retarding color loss. Typical
absorbance curves, represented by 322-6, are shown in Figure II.
Absorbance curves of the rest of the pigment extracts are found
in the Appendix.

The extraction procedure as originally applied to the
flakes was found to be inadequate for removing all of the
pigment. A corrective modification involved adding back enough
water to the flakes to make a thick mash. This was applied
only to the flakes with additive (Table XXXII) to avoid inval-
idating the results obtained from the other flakes (Table XXXI).
This makes comparison between the additive and non-additive flakes
possible only on a relative basis.

Thin layer chromatography was found to be unsatisfactory
for characterizing changes in the pigments during storage.

The reasons for this were the instability of the pigments and
the failure of the sheets used to adequately resolve the

compounds present.

42

Figure II
Title: Visible Spectra of Pigment Extracts
from 322-6 (Without Antioxidant).

Raw potato

Initial flakes

  

-193F 6 mo

5407nm . 320nm

43

 

Table XXXI
Maximum Absorbance of Pigment Extract from
Flakes Without Antioxidant

 

Absorbance

 

 

 

 

 

Sample 0 mo. E 30. 6 mo.

- o 0 -16 i iii
Russet Burbank 0.14 0.12 0.12 0.08 0.06
321-65 0.27 0.27 0.12 0.25 0.06

 

 

Table XXXII
Maximum Absorbance of Pigment Extract
from Flakes With Antioxidant

 

 

 

Absorbance
. 0 mo.5 3mo;:_
Sample :10°F 75°F
Russet Burbank 0.24 0.16 0.14
322-6 0.81 0.76 0.62
321-65 0.68 0.60 0.46

 

44
Sensory Evaluation. Russet Burbank was not different

between -10°F and 75°F for color or flavor. Clones 321-65
and 322-6 were found to be different in color between the two
temperatures. A slight decrease in flavor acceptance was found

for 322-6 after storage at 75°F.

45
SUMMARY AND CONCLUSIONS

In reaching conclusions regarding the processing qual-
ity of the clones studied in this project it is important to
consider that the samples were obtained from one source and
that the production of one year was used. It is most important,
therefore to relate to the commercial varieties used as controls
in making judgements.

The most important characteristics of the potatoes and
their products to be considered in reaching conclusions as to
whether they will be successful varieties are yield per acre
and yield of product, color, and texture.

In coming to some conclusions as to the potential of
the clones, they are divided into those which are unacceptable,
those which are marginal and those which are acceptable.

The unacceptable clones included 1111-2, 706-32, and
706-34. They were judged unacceptable because the products
made from them were of dark color, the texture of the french
fries was not as good as the control, and the product yields
were lower.

The marginal clones were 709, 711-8, and 58. They were
higher in solids and yield and varied in their color and texture
characteristics. Because the response was mixed it is possible
that they would respond well in other seasons or growing condi-
tions.

711-3 was considered to have potential as a conventional

variety. It had slightly higher solids and yields than the

46

marginal clones and had consistently better color. It is rec-
commended that this clone be given greater consideration in
future studies.

The hybrid clones are considered separately because of
their unique properties. Of all the tests run on the potato
products, 321-65 and 322-6 usually gave the best results. They
had higher yields, lighter color, better texture, less 011,
greater bulk density and lower reducing sugars. They are not
lacking disadvantages however. They have a characteristic yellow
flesh due to a high level of xanthophyll pigments. In the
flakes this color is very evident and is unstable unless addi-
tives are used to preserve it. The color may also be unaccep-
table to consumers. It is concluded that three choices exist
for dealing with this problem. One is to preserve the color and
influence consumers to consider it desirable, the second is
to develop a means of bleaching the pigment and the third is
to eliminate the pigment to selective breeding. Other factors
are important in these clones. The flavor of 322-6 was found
to be different by the taste panels and it was found to be
slightly undesirable in the stored flakes. The texture of
chips is different from other varieties. Whether this is good
or bad is not known but the taste panels did detect it. The
french fries were also different, having a dryer texture which
could be undesirable if it is too dry. This is not a problem
in flakes because the moisture in the mashed potatoes made from

them can be adjusted to a desirable level.

4?
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APPENDIX A
INSTRON SHEAR FORCE
CURVES OF FRENCH FRIES

Force (Kg)

 

5#

322-6 Figure III
Title: Instron Shear Force Curves of
French Fries.

Russet 321-65
Burbank

 

 

 

 

A 58 711-3

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Force (Kg)

 

xx‘ru/ ,/ /‘

55

Figure IV
Title: Instron Shear Force Curves of

French Fries.

711-8 1111-2 706-3# 706-32

 

 

 

 

 

 

709

 

 

APPENDIX B

VISIBLE SPECTRA OF
PIGMENT EXTRACTS

56
Figure V
Title: Visible Spectra of Pigment
Extracts From Russet Bur-

bank (Without Antioxidant).

 

 

 

75° 3 mo
raw potato
o
Initial'Flakesgr ‘¢. 75 F 6 mo
" -10°F 6 mo

-10° 3 mo. , ,/"’ I»

/ /

)7”

.Q L-

 

5#0 nm 320 nm

57

Figure VI

Title: Visible Spectre of Pigment
Extracts from Russet Burbank
(With Antioxidant)

~10°F 3 m

3 mo

5&0 nm 320 nm

 

58 E!

Figure VII
Title: Visible Spectra of Pigment Extracts
from 322-6 (With Antioxidant).

raw potato x-

h.

 

Initial

320 nm

59

Figure VIII

Title: Visible Spectra of Pigment
Extracts from 321-65 (Without
Antioxidant).

 

Raw Potato

-10° 3 mo

ll -1o° 6 mo

750 6 mo

Initial Flakes

75° Lmo

 

320 nm

Title:

Raw Pot: .

Init,:

 

60
Figure IX
Visible Spectra of Pigment
Extracts from 321-65 (with
Antioxidant).

320 nm